effect lasted in some instances as long as an hour and
three-quarters after sunset. In India the sun and skies assumed a
greenish hue, and there was much curiosity regarding the cause of the
"green sun." Another remarkable phenomenon of this period was the great
prevalence of rain during the succeeding winter. This probably was due
to the same cause; that is, to the fact of the air being so filled with
dust; the prevailing theory in regard to rain being that the existence
of dust in the air is necessary to its fall. The vapor of the air
concentrates into drops around such minute particles, the result being
that where dust is absent rain cannot fall.

As regards the sunsets spoken of, there are three similar instances on
record. The first of these was in the year 526, when a dry fog covered
the Roman Empire with a red haze. Nothing further is known concerning
it. The other instances were in the years 1783 and 1831. The former of
these has been traced to the great eruption of Skaptur Jokull in that
year. It lasted for several months as a pale blue haze, and occasioned
so much obscurity that the sun was only visible when twelve degrees
above the horizon, and then it had a blood-red appearance. Violent
thunderstorms were associated with it, thus assimilating it with that of
1883. Alike in 1783 and 1831 there was a pearly, phosphorescent gleam in
the atmosphere, by which small print could be read at midnight. We know
nothing regarding the meteorological conditions of 1831.

The red sunsets of 1883 were remarkable for their long persistence.
They were observed in the autumn of 1884 with almost their original
brilliancy, and they were still visible in 1885, being seen at
intervals, as if the dust was then distributed in patches, and driven
about by the winds. In fact, similar sunsets were occasionally visible
for several years afterwards. These may well have been due to the same
cause, when we consider with what extreme slowness very fine dust makes
its way through the air, and how much it may be affected by the winds.

THE RED SUNSETS DESCRIBED

One writer describes the appearance of these sunsets in the following
terms: "Immediately after sunset a patch of white light appeared ten
or fifteen degrees above the horizon, and shone for ten minutes with a
pearly lustre. Beneath it a layer of bright red rested on the horizon,
melting upward into orange, and this passed into yellow light, which
spread around the lucid spot.